Fjölrit RALA - 05.12.1999, Síða 109

RALA Reportno. 200
Desertification in Mongolia
Zambyn Batjargal
National Agency for Meteorology, Hydrology and Environment Monitoring, Khudaldaany gudamj 5,
Uiaanbaatar 46. Mongolia
Tel: 976-1-326592: Fax: 976-1-326611: E-mail: batbaig@magicnet.mn
ABSTRACT
In addition to climatic factors there are several specific human activities that have led to serious and
widespread desertification in Mongolia. Animal husbandry, especially in the arid and semi-arid re-
gions, is considered as the most essential human induced factor affecting desertifícation risk in Mon-
golia. It is an important cause of soil erosion. Grazing pressure is greatest near settlements and water
sources. The carrying capacity of pasture land is frequently exceeded in the areas receiving the great-
est grazing pressure, resulting in degradation of the composition of plant species and soil denudation.
Taking into account the Iong-term experience of pastoralism, several important conclusions are
drawn, including the applicability of the “Clementsian Succession Theory” to Mongolian conditions.
The crop cultivation is an important cause of desertifícation, particularly soil erosion, because spring
tilling coincides with the season of intensive wind. Most of the cultivated areas are devoid of trees or
other windbreaks. It is estimated that over the past 30 years about 35-50 tons of soil have been iost
from each hectare of cultivated land due to wind erosion alone. Half of all cultivated land in Mongolia
is considered to be degraded to some degree of erosion. The annual fluctuation and slow increase in
per-hectare crop yields observed over the last four decades verify this conclusion.
Another factor is deforestation. Most timber harvesting is carried out by clear-cutting. Generally
located on sloped or steep terrain, deforested areas as well as vehicle tracks are particularly subjected
to water erosion. It is estimated that nationwide there are four times as many vehicle tracks as are nec-
essary to ensure access.
Mining and inadequate waste management is also serious factors of land degradation. The devel-
opment of strip mines, as well as the deposition of overburden spoils and tailings all degrade land re-
sources. Domestic and industrial waste is currently deposited on the soil surface in unnecessarily
large, designated dumping sites on the outskirts of cities and towns.
Kev words: desertification, grazing, Mongolia, soil erosion.
INTRODUCTION
In accordance with the Intemational Convention to Combat Desertification (CCD;
United Nations 1994) desertifícation is defmed as land degradation in arid, semi-arid
and dry sub-humid areas resulting from various factors, including climatic variation
and human activities.
Following this defínition, 90% of Mongolian territory can be regarded as vulner-
able to desertification. These areas are almost exclusively used as rangelands, sup-
porting about 30 million heads of livestock and numerous populations of wild ani-
mals. At present time there is no consensus among scientists on climate variations,
particularly on presence or absence of the aridization of Inner Asia and Mongolia. The
coastal formations of many lakes in this area and number of other examples are char-
acteristic for lakes with fluctuating water levels. Now there are certain indications of
lake level rises (for instance, Ubsu-Nuur, Uureg-Nuur in Great Lakes areas of Mon-
golia). At the same time it is necessary to note that this fact might have some relation
to the increase in glacial river flow due to global warming.
Desertification of a territory is usually reflected first of all by dynamics of sand
massifs, which can indicate aridization processes. Sand massifs are the typical land-
scape elements in the majority of inter mountainous depressions of Inner Asia. The
deflation cells and basins among fixed sands are particularly evident in the basin of